Question

求未知数x①23x+12x=42 &...

求未知数x①23x+12x=42 ②x4=30%③1.2：x=0.5：1.5 ④122.4=3x．

Answer 1

①

2

3

x+

1

2

x=42         
        

7

6

x=42
     

7

6

x÷

7

6

=42÷

7

6

          x=36
            
②

x

4

=30%

x

4

×4=30%×4
    x=1.2

③1.2：x=0.5：1.5      
     0.5x=1.2×1.5
0.5x÷0.5=1.8÷0.5
        x=3.6

④

12

2.4

=

3

x

   12x=2.4×3
     x=

2.4×3

12

     x=0.6．